1
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Irwin R, Harkness RW, Forman-Kay JD. A FRET-Based Assay and Computational Tools to Quantify Enzymatic Rates and Explore the Mechanisms of RNA Deadenylases in Heterogeneous Environments. Methods Mol Biol 2024; 2723:69-91. [PMID: 37824065 DOI: 10.1007/978-1-0716-3481-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
We developed a medium-throughput assay that can measure the time-dependent distribution of RNA products generated as a deadenylase degrades a polyadenosine (poly(A)) RNA tract, thereby providing insight into the mechanism of deadenylation. Importantly, this assay can be performed in both homogeneous and heterogeneous environments without relying on gel electrophoresis of RNA products or coupled enzymatic reactions that indirectly report on the RNA distribution through the detection of freed adenosine monophosphate. In parallel, we have established an open-source, Python-based command-line software package, deadenylationkinetics, that can be used to numerically simulate and/or fit the datasets afforded by our assay with different deadenylation mechanisms to determine the most likely case and estimate the associated rate constants. In this chapter, we detail the implementation of our method and the quantification of poly(A) RNA binding and degradation kinetics in application to a truncated version of CNOT7 from the CCR4-NOT deadenylation complex, which serves as a model deadenylase with enhanced activity.
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Affiliation(s)
- Rose Irwin
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Robert W Harkness
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Julie D Forman-Kay
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, ON, Canada.
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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2
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Soeda S, Oyama M, Kozuka-Hata H, Yamamoto T. The CCR4-NOT complex suppresses untimely translational activation of maternal mRNAs. Development 2023; 150:dev201773. [PMID: 37767629 PMCID: PMC10617601 DOI: 10.1242/dev.201773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 09/20/2023] [Indexed: 09/29/2023]
Abstract
Control of mRNA poly(A) tails is essential for regulation of mRNA metabolism, specifically translation efficiency and mRNA stability. Gene expression in maturing oocytes relies largely on post-transcriptional regulation, as genes are transcriptionally silent during oocyte maturation. The CCR4-NOT complex is a major mammalian deadenylase, which regulates poly(A) tails of maternal mRNAs; however, the function of the CCR4-NOT complex in translational regulation has not been well understood. Here, we show that this complex suppresses translational activity of maternal mRNAs during oocyte maturation. Oocytes lacking all CCR4-NOT deadenylase activity owing to genetic deletion of its catalytic subunits, Cnot7 and Cnot8, showed a large-scale gene expression change caused by increased translational activity during oocyte maturation. Developmental arrest during meiosis I in these oocytes resulted in sterility of oocyte-specific Cnot7 and Cnot8 knockout female mice. We further showed that recruitment of CCR4-NOT to maternal mRNAs is mediated by the 3'UTR element CPE, which suppresses translational activation of maternal mRNAs. We propose that suppression of untimely translational activation of maternal mRNAs via deadenylation by CCR4-NOT is essential for proper oocyte maturation.
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Affiliation(s)
- Shou Soeda
- Cell Signal Unit, Okinawa Institute of Science and Technology, Kunigami, 904-0495, Japan
- Laboratory for Cell Systems, Institute for Protein Research, Osaka University, Suita, 565-0871, Japan
| | - Masaaki Oyama
- Medical Proteomics Laboratory, The Institute of Medical Science, The University of Tokyo, Minato-ku, 108-8639, Japan
| | - Hiroko Kozuka-Hata
- Medical Proteomics Laboratory, The Institute of Medical Science, The University of Tokyo, Minato-ku, 108-8639, Japan
| | - Tadashi Yamamoto
- Cell Signal Unit, Okinawa Institute of Science and Technology, Kunigami, 904-0495, Japan
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3
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Quan Y, Wang M, Xu C, Wang X, Wu Y, Qin D, Lin Y, Lu X, Lu F, Li L. Cnot8 eliminates naïve regulation networks and is essential for naïve-to-formative pluripotency transition. Nucleic Acids Res 2022; 50:4414-4435. [PMID: 35390160 PMCID: PMC9071485 DOI: 10.1093/nar/gkac236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 03/11/2022] [Accepted: 03/26/2022] [Indexed: 11/14/2022] Open
Abstract
Mammalian early epiblasts at different phases are characterized by naïve, formative, and primed pluripotency states, involving extensive transcriptome changes. Here, we report that deadenylase Cnot8 of Ccr4-Not complex plays essential roles during the transition from naïve to formative state. Knock out (KO) Cnot8 resulted in early embryonic lethality in mice, but Cnot8 KO embryonic stem cells (ESCs) could be established. Compared with the cells differentiated from normal ESCs, Cnot8 KO cells highly expressed a great many genes during their differentiation into the formative state, including several hundred naïve-like genes enriched in lipid metabolic process and gene expression regulation that may form the naïve regulation networks. Knockdown expression of the selected genes of naïve regulation networks partially rescued the differentiation defects of Cnot8 KO ESCs. Cnot8 depletion led to the deadenylation defects of its targets, increasing their poly(A) tail lengths and half-life, eventually elevating their expression levels. We further found that Cnot8 was involved in the clearance of targets through its deadenylase activity and the binding of Ccr4-Not complex, as well as the interacting with Tob1 and Pabpc1. Our results suggest that Cnot8 eliminates naïve regulation networks through mRNA clearance, and is essential for naïve-to-formative pluripotency transition.
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Affiliation(s)
- Yujun Quan
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Meijiao Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Chengpeng Xu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoxiao Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu Wu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dandan Qin
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuxuan Lin
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xukun Lu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Falong Lu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Stem Cell and Regeneration, Beijing Institute of Stem Cell and Regenerative Medicine, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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4
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Mishima Y, Han P, Ishibashi K, Kimura S, Iwasaki S. Ribosome slowdown triggers codon-mediated mRNA decay independently of ribosome quality control. EMBO J 2022; 41:e109256. [PMID: 35040509 PMCID: PMC8886528 DOI: 10.15252/embj.2021109256] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 12/11/2022] Open
Abstract
The control of mRNA stability plays a central role in regulating gene expression patterns. Recent studies have revealed that codon composition in the open reading frame determines mRNA stability in multiple organisms. Based on genome-wide correlation approaches, this previously unrecognized role for the genetic code is attributable to the kinetics of the codon-decoding process by the ribosome. However, complementary experimental analyses are required to clarify the codon effects on mRNA stability and the related cotranslational mRNA decay pathways, for example, those triggered by aberrant ribosome stalling. In the current study, we performed a set of reporter-based analyses to define codon-mediated mRNA decay and ribosome stall-dependent mRNA decay in zebrafish embryos. Our analysis showed that the effect of codons on mRNA stability stems from the decoding process, independent of the ribosome quality control factor Znf598 and stalling-dependent mRNA decay. We propose that codon-mediated mRNA decay is rather triggered by transiently slowed ribosomes engaging in a productive translation cycle in zebrafish embryos.
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Affiliation(s)
- Yuichiro Mishima
- Department of Frontier Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan,RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan
| | - Peixun Han
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan,Department of Computational Biology and Medical SciencesGraduate School of Frontier SciencesThe University of TokyoChibaJapan
| | - Kota Ishibashi
- Department of Frontier Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan
| | - Seisuke Kimura
- Department of Industrial Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan,Center for Plant SciencesKyoto Sangyo UniversityKyotoJapan
| | - Shintaro Iwasaki
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan,Department of Computational Biology and Medical SciencesGraduate School of Frontier SciencesThe University of TokyoChibaJapan
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5
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Stoney PN, Yanagiya A, Nishijima S, Yamamoto T. CNOT7 outcompetes its paralog CNOT8 for integration into the CCR4-NOT complex. J Mol Biol 2022; 434:167523. [DOI: 10.1016/j.jmb.2022.167523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/08/2022] [Accepted: 02/28/2022] [Indexed: 02/07/2023]
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6
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Roles of mRNA poly(A) tails in regulation of eukaryotic gene expression. Nat Rev Mol Cell Biol 2022; 23:93-106. [PMID: 34594027 PMCID: PMC7614307 DOI: 10.1038/s41580-021-00417-y] [Citation(s) in RCA: 200] [Impact Index Per Article: 100.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2021] [Indexed: 02/06/2023]
Abstract
In eukaryotes, poly(A) tails are present on almost every mRNA. Early experiments led to the hypothesis that poly(A) tails and the cytoplasmic polyadenylate-binding protein (PABPC) promote translation and prevent mRNA degradation, but the details remained unclear. More recent data suggest that the role of poly(A) tails is much more complex: poly(A)-binding protein can stimulate poly(A) tail removal (deadenylation) and the poly(A) tails of stable, highly translated mRNAs at steady state are much shorter than expected. Furthermore, the rate of translation elongation affects deadenylation. Consequently, the interplay between poly(A) tails, PABPC, translation and mRNA decay has a major role in gene regulation. In this Review, we discuss recent work that is revolutionizing our understanding of the roles of poly(A) tails in the cytoplasm. Specifically, we discuss the roles of poly(A) tails in translation and control of mRNA stability and how poly(A) tails are removed by exonucleases (deadenylases), including CCR4-NOT and PAN2-PAN3. We also discuss how deadenylation rate is determined, the integration of deadenylation with other cellular processes and the function of PABPC. We conclude with an outlook for the future of research in this field.
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7
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Akiyama T, Yamamoto T. Regulation of Early Lymphocyte Development via mRNA Decay Catalyzed by the CCR4-NOT Complex. Front Immunol 2021; 12:715675. [PMID: 34349771 PMCID: PMC8326961 DOI: 10.3389/fimmu.2021.715675] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
Development of lymphocytes is precisely regulated by various mechanisms. In addition to transcriptional rates, post-transcriptional regulation of mRNA abundance contributes to differentiation of lymphocytes. mRNA decay is a post-transcriptional mechanism controlling mRNA abundance. The carbon catabolite repression 4 (CCR4)-negative on TATA-less (NOT) complex controls mRNA longevity by catalyzing mRNA deadenylation, which is the rate-limiting step in the mRNA decay pathway. mRNA decay, regulated by the CCR4-NOT complex, is required for differentiation of pro-B to pre-B cells and V(D)J recombination in pro-B cells. In this process, it is likely that the RNA-binding proteins, ZFP36 ring finger protein like 1 and 2, recruit the CCR4-NOT complex to specific target mRNAs, thereby inducing cell quiescence of pro-B cells. A recent study showed that the CCR4-NOT complex participates in positive selection of thymocytes. Mechanistically, the CCR4-NOT deadenylase complex inhibits abnormal apoptosis by reducing the expression level of mRNAs encoding pro-apoptotic proteins, which are otherwise up-regulated during positive selection. We discuss mechanisms regulating CCR4-NOT complex-dependent mRNA decay in lymphocyte development and selection.
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Affiliation(s)
- Taishin Akiyama
- Laboratory for Immune Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan.,Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Tadashi Yamamoto
- Cell Signal Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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8
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Chen Y, Khazina E, Izaurralde E, Weichenrieder O. Crystal structure and functional properties of the human CCR4-CAF1 deadenylase complex. Nucleic Acids Res 2021; 49:6489-6510. [PMID: 34038562 PMCID: PMC8216464 DOI: 10.1093/nar/gkab414] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 04/28/2021] [Accepted: 05/05/2021] [Indexed: 01/07/2023] Open
Abstract
The CCR4 and CAF1 deadenylases physically interact to form the CCR4-CAF1 complex and function as the catalytic core of the larger CCR4-NOT complex. Together, they are responsible for the eventual removal of the 3′-poly(A) tail from essentially all cellular mRNAs and consequently play a central role in the posttranscriptional regulation of gene expression. The individual properties of CCR4 and CAF1, however, and their respective contributions in different organisms and cellular environments are incompletely understood. Here, we determined the crystal structure of a human CCR4-CAF1 complex and characterized its enzymatic and substrate recognition properties. The structure reveals specific molecular details affecting RNA binding and hydrolysis, and confirms the CCR4 nuclease domain to be tethered flexibly with a considerable distance between both enzyme active sites. CCR4 and CAF1 sense nucleotide identity on both sides of the 3′-terminal phosphate, efficiently differentiating between single and consecutive non-A residues. In comparison to CCR4, CAF1 emerges as a surprisingly tunable enzyme, highly sensitive to pH, magnesium and zinc ions, and possibly allowing distinct reaction geometries. Our results support a picture of CAF1 as a primordial deadenylase, which gets assisted by CCR4 for better efficiency and by the assembled NOT proteins for selective mRNA targeting and regulation.
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Affiliation(s)
- Ying Chen
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elena Khazina
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elisa Izaurralde
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Oliver Weichenrieder
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
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9
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Akiyama T, Suzuki T, Yamamoto T. RNA decay machinery safeguards immune cell development and immunological responses. Trends Immunol 2021; 42:447-460. [PMID: 33858774 DOI: 10.1016/j.it.2021.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 12/30/2022]
Abstract
mRNA decay systems control mRNA abundance by counterbalancing transcription. Several recent studies show that mRNA decay pathways are crucial to conventional T and B cell development in vertebrates, in addition to suppressing autoimmunity and excessive inflammatory responses. Selective mRNA degradation triggered by the CCR4-NOT deadenylase complex appears to be required in lymphocyte development, cell quiescence, V(D)J (variable-diversity-joining) recombination, and prevention of inappropriate apoptosis in mice. Moreover, a recent study suggests that mRNA decay may be involved in preventing human hyperinflammatory disease. These findings imply that mRNA decay pathways in humans and mice do not simply maintain mRNA homeostatic turnover but can also precisely regulate immune development and immunological responses by selectively targeting mRNAs.
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Affiliation(s)
- Taishin Akiyama
- Laboratory for Immune Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; Graduate School of Medical Life Science, Yokohama City University, Yokohama 230-0045, Japan.
| | - Toru Suzuki
- Laboratory for Immunogenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Tadashi Yamamoto
- Laboratory for Immunogenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; Cell Signal Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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10
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Ye X, Axhemi A, Jankowsky E. Alternative RNA degradation pathways by the exonuclease Pop2p from Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2021; 27:465-476. [PMID: 33408095 PMCID: PMC7962489 DOI: 10.1261/rna.078006.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 12/31/2020] [Indexed: 06/12/2023]
Abstract
The 3' to 5' exonuclease Pop2p (Caf1p) is part of the CCR4-NOT deadenylation complex that removes poly(A) tails from mRNAs in cells. Pop2p is structurally conserved in eukaryotes, but Saccharomyces cerevisiae Pop2p harbors noncanonical amino acids in its catalytic center. The enzymatic properties of S. cerevisiae Pop2p are not well defined. Here we characterize the RNA exonuclease activity of recombinant S. cerevisiae Pop2p. We find that S. cerevisiae Pop2p degrades RNAs via two alternative reactions pathways, one generating nucleotides with 5'-phosphates and RNA intermediates with 3'-hydroxyls, and the other generating nucleotides with 3'-phosphates and RNA intermediates with 3'-phosphates. The enzyme is not able to initiate the reaction on RNAs with a 3'-phosphate, which leads to accumulation of RNAs with 3'-phosphates that can exceed 10 nt and are resistant to further degradation by S. cerevisiae Pop2p. We further demonstrate that S. cerevisiae Pop2p degrades RNAs in three reaction phases: an initial distributive phase, a second processive phase and a third phase during which processivity gradually declines. We also show that mutations of subsets of amino acids in the catalytic center, including those previously thought to inactivate the enzyme, moderately reduce, but not eliminate activity. Only mutation of all five amino acids in the catalytic center diminishes activity of Pop2p to background levels. Collectively, our results reveal robust exonuclease activity of S. cerevisiae Pop2p with unusual enzymatic properties, characterized by alternative degradation pathways, multiple reaction phases and functional redundancy of amino acids in the catalytic core.
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Affiliation(s)
- Xuan Ye
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Armend Axhemi
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Eckhard Jankowsky
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
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11
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Kandasamy G, Pradhan AK, Palanimurugan R. Ccr4-Not complex subunits Ccr4, Caf1, and Not4 are novel proteolysis factors promoting the degradation of ubiquitin-dependent substrates by the 26S proteasome. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119010. [PMID: 33727038 DOI: 10.1016/j.bbamcr.2021.119010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 02/16/2021] [Accepted: 03/07/2021] [Indexed: 12/22/2022]
Abstract
Degradation of short-lived and abnormal proteins is essential for normal cellular homeostasis. In eukaryotes, such unstable cellular proteins are selectively degraded by the ubiquitin proteasome system (UPS). Abnormalities in protein degradation by the UPS have been linked to several human diseases. Ccr4, Caf1, and Not4 proteins are known components of the Ccr4-Not multimeric complex. Ccr4 and Caf1 have established roles in transcription, mRNA de-adenylation and RNA degradation etc., while Not4 was shown to have important roles in regulating translation and protein quality control pathways. Here we show that Ccr4, Caf1, and Not4 have a novel function at a post-ubiquitylation step in the UPS pathway by promoting ubiquitin-dependent degradation of short-lived proteins by the 26S proteasome. Using a substrate of the well-studied ubiquitin fusion degradation (UFD) pathway, we found that its UPS-mediated degradation was severely impaired upon deletion of CCR4, CAF1, or NOT4 genes in Saccharomyces cerevisiae. Additionally, we show that Ccr4, Caf1, and Not4 bind to cellular ubiquitin conjugates, and that Ccr4 and Caf1 proteins interact with the proteasome. In contrast to Ccr4, Caf1, and Not4, other subunits of the Ccr4-Not complex are dispensable for UFD substrate degradation. From our findings we conclude that the Ccr4-Not complex subunits Ccr4, Caf1, and Not4 have a novel function outside of the canonical Ccr4-Not complex as a factor targeting ubiquitylated substrates for proteasomal degradation.
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Affiliation(s)
- Ganapathi Kandasamy
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, Telangana, India.
| | - Ashis Kumar Pradhan
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, Telangana, India
| | - R Palanimurugan
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, Telangana, India
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12
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Cristodero M, Brogli R, Joss O, Schimanski B, Schneider A, Polacek N. tRNA 3' shortening by LCCR4 as a response to stress in Trypanosoma brucei. Nucleic Acids Res 2021; 49:1647-1661. [PMID: 33406257 PMCID: PMC7897491 DOI: 10.1093/nar/gkaa1261] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 11/24/2020] [Accepted: 12/19/2020] [Indexed: 12/27/2022] Open
Abstract
Sensing of environmental cues is crucial for cell survival. To adapt to changes in their surroundings cells need to tightly control the repertoire of genes expressed at any time. Regulation of translation is key, especially in organisms in which transcription is hardly controlled, like Trypanosoma brucei. In this study, we describe the shortening of the bulk of the cellular tRNAs during stress at the expense of the conserved 3' CCA-tail. This tRNA shortening is specific for nutritional stress and renders tRNAs unsuitable substrates for translation. We uncovered the nuclease LCCR4 (Tb927.4.2430), a homologue of the conserved deadenylase Ccr4, as being responsible for tRNA trimming. Once optimal growth conditions are restored tRNAs are rapidly repaired by the trypanosome tRNA nucleotidyltransferase thus rendering the recycled tRNAs amenable for translation. This mechanism represents a fast and efficient way to repress translation during stress, allowing quick reactivation with a low energy input.
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Affiliation(s)
| | - Rebecca Brogli
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Oliver Joss
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Bernd Schimanski
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Norbert Polacek
- Correspondence may also be addressed to Norbert Polacek. Tel: +41 031 631 4320;
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13
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The CCR4-NOT Complex Maintains Stability and Transcription of rRNA Genes by Repressing Antisense Transcripts. Mol Cell Biol 2019; 40:MCB.00320-19. [PMID: 31611247 PMCID: PMC6908257 DOI: 10.1128/mcb.00320-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/26/2019] [Indexed: 12/21/2022] Open
Abstract
The rRNA genes (rDNA) in eukaryotes are organized into highly repetitive gene clusters. Each organism maintains a particular number of copies, suggesting that the rDNA is actively stabilized. We previously identified about 700 Saccharomyces cerevisiae genes that could contribute to rDNA maintenance. Here, we further analyzed these deletion mutants with unstable rDNA by measuring the amounts of extrachromosomal rDNA circles (ERCs) that are released as by-products of intrachromosomal recombination. The rRNA genes (rDNA) in eukaryotes are organized into highly repetitive gene clusters. Each organism maintains a particular number of copies, suggesting that the rDNA is actively stabilized. We previously identified about 700 Saccharomyces cerevisiae genes that could contribute to rDNA maintenance. Here, we further analyzed these deletion mutants with unstable rDNA by measuring the amounts of extrachromosomal rDNA circles (ERCs) that are released as by-products of intrachromosomal recombination. We found that extremely high levels of ERCs were formed in the absence of Pop2 (Caf1), which is a subunit of the CCR4-NOT complex, important for the regulation of all stages of gene expression. In the pop2 mutant, transcripts from the noncoding promoter E-pro in the rDNA accumulated, and the amounts of cohesin and condensin were reduced, which could promote recombination events. Moreover, we discovered that the amount of rRNA was decreased in the pop2 mutant. Similar phenotypes were observed in the absence of subunits Ccr4 and Not4 that, like Pop2, convey enzymatic activity to the complex. These findings indicate that lack of any CCR4-NOT-associated enzymatic activity resulted in a severe unstable rDNA phenotype related to the accumulation of noncoding RNA from E-pro.
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14
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Abshire ET, Chasseur J, Bohn JA, Del Rizzo PA, Freddolino PL, Goldstrohm AC, Trievel RC. The structure of human Nocturnin reveals a conserved ribonuclease domain that represses target transcript translation and abundance in cells. Nucleic Acids Res 2019; 46:6257-6270. [PMID: 29860338 PMCID: PMC6158716 DOI: 10.1093/nar/gky412] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 05/09/2018] [Indexed: 12/22/2022] Open
Abstract
The circadian protein Nocturnin (NOCT) belongs to the exonuclease, endonuclease and phosphatase superfamily and is most similar to the CCR4-class of deadenylases that degrade the poly-adenosine tails of mRNAs. NOCT-deficient mice are resistant to high-fat diet induced weight gain, and exhibit dysregulation of bone formation. However, the mechanisms by which NOCT regulates these processes remain to be determined. Here, we describe a pair of high-resolution crystal structures of the human NOCT catalytic domain. The active site of NOCT is highly conserved with other exoribonucleases, and when directed to a transcript in cells, NOCT can reduce translation and abundance of that mRNA in a manner dependent on key active site residues. In contrast to the related deadenylase CNOT6L, purified recombinant NOCT lacks in vitro ribonuclease activity, suggesting that unidentified factors are necessary for enzymatic activity. We also find the ability of NOCT to repress reporter mRNAs in cells depends upon the 3' end of the mRNA, as reporters terminating with a 3' MALAT1 structure cannot be repressed by NOCT. Together, these data demonstrate that NOCT is an exoribonuclease that can degrade mRNAs to inhibit protein expression, suggesting a molecular mechanism for its regulatory role in lipid metabolism and bone development.
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Affiliation(s)
- Elizabeth T Abshire
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jennifer Chasseur
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jennifer A Bohn
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul A Del Rizzo
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Aaron C Goldstrohm
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Raymond C Trievel
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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15
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Amaya Ramirez CC, Hubbe P, Mandel N, Béthune J. 4EHP-independent repression of endogenous mRNAs by the RNA-binding protein GIGYF2. Nucleic Acids Res 2019; 46:5792-5808. [PMID: 29554310 PMCID: PMC6009589 DOI: 10.1093/nar/gky198] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 03/07/2018] [Indexed: 11/12/2022] Open
Abstract
Initially identified as a factor involved in tyrosine kinase receptor signaling, Grb10-interacting GYF protein 2 (GIGYF2) has later been shown to interact with the 5′ cap-binding protein 4EHP as part of a translation repression complex, and to mediate post-transcriptional repression of tethered reporter mRNAs. A current model proposes that GIGYF2 is indirectly recruited to mRNAs by specific RNA-binding proteins (RBPs) leading to translation repression through its association with 4EHP. Accordingly, we recently observed that GIGYF2 also interacts with the miRNA-induced silencing complex and probably modulates its translation repression activity. Here we have further investigated how GIGYF2 represses mRNA function. In a tethering reporter assay, we identify three independent domains of GIGYF2 with repressive activity. In this assay, GIGYF2-mediated repression is independent of 4EHP but largely dependent on the CCR4/NOT complex that GIGYF2 recruits through multiple interfaces. Importantly, we show that GIGYF2 is an RBP and identify for the first time endogenous mRNA targets that recapitulate 4EHP-independent repression. Altogether, we propose that GIGYF2 has two distinct mechanisms of repression: one depends on 4EHP binding and mainly affects translation; the other is 4EHP-independent and involves the CCR4/NOT complex and its deadenylation activity.
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Affiliation(s)
- Cinthia C Amaya Ramirez
- CellNetworks Junior Research Group Posttranscriptional Regulation of mRNA Expression and Localization, Heidelberg University, D-69120 Heidelberg, Germany.,Biochemistry Center, Heidelberg University, D-69120 Heidelberg, Germany
| | - Petra Hubbe
- CellNetworks Junior Research Group Posttranscriptional Regulation of mRNA Expression and Localization, Heidelberg University, D-69120 Heidelberg, Germany.,Biochemistry Center, Heidelberg University, D-69120 Heidelberg, Germany
| | - Nicolas Mandel
- CellNetworks Junior Research Group Posttranscriptional Regulation of mRNA Expression and Localization, Heidelberg University, D-69120 Heidelberg, Germany.,Biochemistry Center, Heidelberg University, D-69120 Heidelberg, Germany
| | - Julien Béthune
- CellNetworks Junior Research Group Posttranscriptional Regulation of mRNA Expression and Localization, Heidelberg University, D-69120 Heidelberg, Germany.,Biochemistry Center, Heidelberg University, D-69120 Heidelberg, Germany
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16
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Airhihen B, Pavanello L, Jadhav GP, Fischer PM, Winkler GS. 1-Hydroxy-xanthine derivatives inhibit the human Caf1 nuclease and Caf1-containing nuclease complexes via Mg 2+-dependent binding. FEBS Open Bio 2019; 9:717-727. [PMID: 30984545 PMCID: PMC6443996 DOI: 10.1002/2211-5463.12605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/18/2019] [Accepted: 02/07/2019] [Indexed: 01/11/2023] Open
Abstract
In eukaryotic cells, cytoplasmic mRNA is characterised by a 3′ poly(A) tail. The shortening and removal of poly(A) tails (deadenylation) by the Ccr4‐Not nuclease complex leads to reduced translational efficiency and RNA degradation. Using recombinant human Caf1 (CNOT7) enzyme as a screening tool, we recently described the discovery and synthesis of a series of substituted 1‐hydroxy‐3,7‐dihydro‐1H‐purine‐2,6‐diones (1‐hydroxy‐xanthines) as inhibitors of the Caf1 catalytic subunit of the Ccr4‐Not complex. Here, we used a chemiluminescence‐based AMP detection assay to show that active 1‐hydroxy‐xanthines inhibit both isolated Caf1 enzyme and human Caf1‐containing complexes that also contain the second nuclease subunit Ccr4 (CNOT6L) to a similar extent, indicating that the active site of the Caf1 nuclease subunit does not undergo substantial conformational change when bound to other Ccr4‐Not subunits. Using differential scanning fluorimetry, we also show that binding of active 1‐hydroxy‐xanthines requires the presence of Mg2+ ions, which are present in the active site of Caf1.
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Affiliation(s)
- Blessing Airhihen
- School of Pharmacy University of Nottingham UK.,Present address: Department of Pharmacology School of Pharmacy Niger Delta University Wilberforce Island Nigeria
| | - Lorenzo Pavanello
- School of Pharmacy University of Nottingham UK.,Present address: Domainex Ltd Chesterford Research Park Little Chesterford, Saffron Walden, Essex UK
| | - Gopal P Jadhav
- School of Pharmacy Centre for Biomolecular Sciences University of Nottingham UK.,Present address: School of Medicine Department of Clinical & Translational Sciences Creighton University Omaha NE USA
| | - Peter M Fischer
- School of Pharmacy Centre for Biomolecular Sciences University of Nottingham UK
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17
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PABP Cooperates with the CCR4-NOT Complex to Promote mRNA Deadenylation and Block Precocious Decay. Mol Cell 2019; 70:1081-1088.e5. [PMID: 29932901 DOI: 10.1016/j.molcel.2018.05.009] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/16/2018] [Accepted: 05/04/2018] [Indexed: 12/18/2022]
Abstract
Multiple deadenylases are known in vertebrates, the PAN2-PAN3 (PAN2/3) and CCR4-NOT (CNOT) complexes, and PARN, yet their differential functions remain ambiguous. Moreover, the role of poly(A) binding protein (PABP) is obscure, limiting our understanding of the deadenylation mechanism. Here, we show that CNOT serves as a predominant nonspecific deadenylase for cytoplasmic poly(A)+ RNAs, and PABP promotes deadenylation while preventing premature uridylation and decay. PAN2/3 selectively trims long tails (>∼150 nt) with minimal effect on transcriptome, whereas PARN does not affect mRNA deadenylation. CAF1 and CCR4, catalytic subunits of CNOT, display distinct activities: CAF1 trims naked poly(A) segments and is blocked by PABPC, whereas CCR4 is activated by PABPC to shorten PABPC-protected sequences. Concerted actions of CAF1 and CCR4 delineate the ∼27 nt periodic PABPC footprints along shortening tail. Our study unveils distinct functions of deadenylases and PABPC, re-drawing the view on mRNA deadenylation and regulation.
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18
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Webster MW, Chen YH, Stowell JAW, Alhusaini N, Sweet T, Graveley BR, Coller J, Passmore LA. mRNA Deadenylation Is Coupled to Translation Rates by the Differential Activities of Ccr4-Not Nucleases. Mol Cell 2019; 70:1089-1100.e8. [PMID: 29932902 PMCID: PMC6024076 DOI: 10.1016/j.molcel.2018.05.033] [Citation(s) in RCA: 147] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/17/2018] [Accepted: 05/24/2018] [Indexed: 01/01/2023]
Abstract
Translation and decay of eukaryotic mRNAs is controlled by shortening of the poly(A) tail and release of the poly(A)-binding protein Pab1/PABP. The Ccr4-Not complex contains two exonucleases—Ccr4 and Caf1/Pop2—that mediate mRNA deadenylation. Here, using a fully reconstituted biochemical system with proteins from the fission yeast Schizosaccharomyces pombe, we show that Pab1 interacts with Ccr4-Not, stimulates deadenylation, and differentiates the roles of the nuclease enzymes. Surprisingly, Pab1 release relies on Ccr4 activity. In agreement with this, in vivo experiments in budding yeast show that Ccr4 is a general deadenylase that acts on all mRNAs. In contrast, Caf1 only trims poly(A) not bound by Pab1. As a consequence, Caf1 is a specialized deadenylase required for the selective deadenylation of transcripts with lower rates of translation elongation and reduced Pab1 occupancy. These findings reveal a coupling between the rates of translation and deadenylation that is dependent on Pab1 and Ccr4-Not. Poly(A)-binding protein is efficiently released by Ccr4-Not nuclease activity Ccr4, but not Caf1, removes poly(A) tails bound to Pab1 Ccr4 acts on all transcripts and Caf1 acts on transcripts with low codon optimality Deadenylation by Ccr4-Not connects translation with mRNA stability
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Affiliation(s)
| | - Ying-Hsin Chen
- The Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106-4960, USA
| | | | - Najwa Alhusaini
- The Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106-4960, USA
| | - Thomas Sweet
- The Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106-4960, USA
| | - Brenton R Graveley
- Department of Genetics and Developmental Biology, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Jeff Coller
- The Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106-4960, USA.
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19
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The central region of CNOT1 and CNOT9 stimulates deadenylation by the Ccr4-Not nuclease module. Biochem J 2018; 475:3437-3450. [PMID: 30309886 DOI: 10.1042/bcj20180456] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 12/12/2022]
Abstract
Regulated degradation of cytoplasmic mRNA is important for the accurate execution of gene expression programmes in eukaryotic cells. A key step in this process is the shortening and removal of the mRNA poly(A) tail, which can be achieved by the recruitment of the multi-subunit Ccr4-Not nuclease complex via sequence-specific RNA-binding proteins or the microRNA machinery. The Ccr4-Not complex contains several modules that are attached to its large subunit CNOT1. Modules include the nuclease module, which associates with the MIF4G domain of CNOT1 and contains the catalytic subunits Caf1 and Ccr4, as well as the module containing the non-catalytic CNOT9 subunit, which binds to the DUF3819 domain of CNOT1. To understand the contributions of the individual modules to the activity of the complex, we have started to reconstitute sub-complexes of the human Ccr4-Not complex containing one or several functional modules. Here, we report the reconstitution of a pentameric complex including a BTG2-Caf1-Ccr4 nuclease module, CNOT9 and the central region of CNOT1 encompassing the MIF4G and DUF3819 domains. By comparing the biochemical activities of the pentameric complex and the nuclease module, we conclude that the CNOT1-CNOT9 components stimulate deadenylation by the nuclease module. In addition, we show that a pentameric complex containing the melanoma-associated CNOT9 P131L variant is able to support deadenylation similar to a complex containing the wild-type CNOT9 protein.
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20
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Chen H, Sirupangi T, Wu ZH, Johnson DL, Laribee RN. The conserved RNA recognition motif and C3H1 domain of the Not4 ubiquitin ligase regulate in vivo ligase function. Sci Rep 2018; 8:8163. [PMID: 29802328 PMCID: PMC5970261 DOI: 10.1038/s41598-018-26576-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 05/16/2018] [Indexed: 11/09/2022] Open
Abstract
The Ccr4-Not complex controls RNA polymerase II (Pol II) dependent gene expression and proteasome function. The Not4 ubiquitin ligase is a Ccr4-Not subunit that has both a RING domain and a conserved RNA recognition motif and C3H1 domain (referred to as the RRM-C domain) with unknown function. We demonstrate that while individual Not4 RING or RRM-C mutants fail to replicate the proteasomal defects found in Not4 deficient cells, mutation of both exhibits a Not4 loss of function phenotype. Transcriptome analysis revealed that the Not4 RRM-C affects a specific subset of Pol II-regulated genes, including those involved in transcription elongation, cyclin-dependent kinase regulated nutrient responses, and ribosomal biogenesis. The Not4 RING, RRM-C, or RING/RRM-C mutations cause a generalized increase in Pol II binding at a subset of these genes, yet their impact on gene expression does not always correlate with Pol II recruitment which suggests Not4 regulates their expression through additional mechanisms. Intriguingly, we find that while the Not4 RRM-C is dispensable for Ccr4-Not association with RNA Pol II, the Not4 RING domain is required for these interactions. Collectively, these data elucidate previously unknown roles for the conserved Not4 RRM-C and RING domains in regulating Ccr4-Not dependent functions in vivo.
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Affiliation(s)
- Hongfeng Chen
- Department of Pathology and Laboratory Medicine, and Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, 38163, United States of America
| | - Tirupataiah Sirupangi
- Department of Pathology and Laboratory Medicine, and Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, 38163, United States of America
| | - Zhao-Hui Wu
- Department of Pathology and Laboratory Medicine, and Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, 38163, United States of America
| | - Daniel L Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, 38163, United States of America
| | - R Nicholas Laribee
- Department of Pathology and Laboratory Medicine, and Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, 38163, United States of America.
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21
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Abstract
Poly(A) tails are found at the 3' end of almost every eukaryotic mRNA and are important for the stability of mRNAs and their translation into proteins. Thus, removal of the poly(A) tail, a process called deadenylation, is critical for regulation of gene expression. Most deadenylation enzymes are components of large multi-protein complexes. Here, we describe an in vitro deadenylation assay developed to study the exonucleolytic activities of the multi-protein Ccr4-Not and Pan2-Pan3 complexes. We discuss how this assay can be used with short synthetic RNAs, as well as longer RNA substrates generated using in vitro transcription. Importantly, quantitation of the reactions allows detailed analyses of deadenylation in the presence and absence of accessory factors, leading to new insights into targeted mRNA decay.
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22
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Łabno A, Tomecki R, Dziembowski A. Cytoplasmic RNA decay pathways - Enzymes and mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:3125-3147. [PMID: 27713097 DOI: 10.1016/j.bbamcr.2016.09.023] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 12/14/2022]
Abstract
RNA decay plays a crucial role in post-transcriptional regulation of gene expression. Work conducted over the last decades has defined the major mRNA decay pathways, as well as enzymes and their cofactors responsible for these processes. In contrast, our knowledge of the mechanisms of degradation of non-protein coding RNA species is more fragmentary. This review is focused on the cytoplasmic pathways of mRNA and ncRNA degradation in eukaryotes. The major 3' to 5' and 5' to 3' mRNA decay pathways are described with emphasis on the mechanisms of their activation by the deprotection of RNA ends. More recently discovered 3'-end modifications such as uridylation, and their relevance to cytoplasmic mRNA decay in various model organisms, are also discussed. Finally, we provide up-to-date findings concerning various pathways of non-coding RNA decay in the cytoplasm.
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Affiliation(s)
- Anna Łabno
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Rafał Tomecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland.
| | - Andrzej Dziembowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland.
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23
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Niinuma S, Fukaya T, Tomari Y. CCR4 and CAF1 deadenylases have an intrinsic activity to remove the post-poly(A) sequence. RNA (NEW YORK, N.Y.) 2016; 22:1550-1559. [PMID: 27484313 PMCID: PMC5029453 DOI: 10.1261/rna.057679.116] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/21/2016] [Indexed: 05/31/2023]
Abstract
MicroRNAs (miRNAs) recruit the CCR4-NOT complex, which contains two deadenylases, CCR4 and CAF1, to promote shortening of the poly(A) tail. Although both CCR4 and CAF1 generally have a strong preference for poly(A) RNA substrates, it has been reported from yeast to humans that they can also remove non-A residues in vitro to various degrees. However, it remains unknown how CCR4 and CAF1 remove non-A sequences. Herein we show that Drosophila miRNAs can promote the removal of 3'-terminal non-A residues in an exonucleolytic manner, but only if an upstream poly(A) sequence exists. This non-A removing reaction is directly catalyzed by both CCR4 and CAF1 and depends on the balance between the length of the internal poly(A) sequence and that of the downstream non-A sequence. These results suggest that the CCR4-NOT complex has an intrinsic activity to remove the 3'-terminal non-A modifications downstream from the poly(A) tail.
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Affiliation(s)
- Sho Niinuma
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, JapanDepartment of Computational Biology and Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takashi Fukaya
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, JapanDepartment of Computational Biology and Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yukihide Tomari
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, JapanDepartment of Computational Biology and Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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24
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Wang X, Xi W, Toomey S, Chiang YC, Hasek J, Laue TM, Denis CL. Stoichiometry and Change of the mRNA Closed-Loop Factors as Translating Ribosomes Transit from Initiation to Elongation. PLoS One 2016; 11:e0150616. [PMID: 26953568 PMCID: PMC4783044 DOI: 10.1371/journal.pone.0150616] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/17/2016] [Indexed: 01/06/2023] Open
Abstract
Protein synthesis is a highly efficient process and is under exacting control. Yet, the actual abundance of translation factors present in translating complexes and how these abundances change during the transit of a ribosome across an mRNA remains unknown. Using analytical ultracentrifugation with fluorescent detection we have determined the stoichiometry of the closed-loop translation factors for translating ribosomes. A variety of pools of translating polysomes and monosomes were identified, each containing different abundances of the closed-loop factors eIF4E, eIF4G, and PAB1 and that of the translational repressor, SBP1. We establish that closed-loop factors eIF4E/eIF4G dissociated both as ribosomes transited polyadenylated mRNA from initiation to elongation and as translation changed from the polysomal to monosomal state prior to cessation of translation. eIF4G was found to particularly dissociate from polyadenylated mRNA as polysomes moved to the monosomal state, suggesting an active role for translational repressors in this process. Consistent with this suggestion, translating complexes generally did not simultaneously contain eIF4E/eIF4G and SBP1, implying mutual exclusivity in such complexes. For substantially deadenylated mRNA, however, a second type of closed-loop structure was identified that contained just eIF4E and eIF4G. More than one eIF4G molecule per polysome appeared to be present in these complexes, supporting the importance of eIF4G interactions with the mRNA independent of PAB1. These latter closed-loop structures, which were particularly stable in polysomes, may be playing specific roles in both normal and disease states for specific mRNA that are deadenylated and/or lacking PAB1. These analyses establish a dynamic snapshot of molecular abundance changes during ribosomal transit across an mRNA in what are likely to be critical targets of regulation.
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Affiliation(s)
- Xin Wang
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, United States of America
| | - Wen Xi
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, United States of America
| | - Shaun Toomey
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, United States of America
| | - Yueh-Chin Chiang
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, United States of America
| | - Jiri Hasek
- Laboratory of Cell Reproduction, Institute of Microbiology of ASCR, Prague, Videnska 1083, Czech Republic
| | - Thomas M. Laue
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, United States of America
| | - Clyde L. Denis
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, United States of America
- * E-mail:
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25
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Faraji F, Hu Y, Yang HH, Lee MP, Winkler GS, Hafner M, Hunter KW. Post-transcriptional Control of Tumor Cell Autonomous Metastatic Potential by CCR4-NOT Deadenylase CNOT7. PLoS Genet 2016; 12:e1005820. [PMID: 26807845 PMCID: PMC4726497 DOI: 10.1371/journal.pgen.1005820] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/31/2015] [Indexed: 12/15/2022] Open
Abstract
Accumulating evidence supports the role of an aberrant transcriptome as a driver of metastatic potential. Deadenylation is a general regulatory node for post-transcriptional control by microRNAs and other determinants of RNA stability. Previously, we demonstrated that the CCR4-NOT scaffold component Cnot2 is an inherited metastasis susceptibility gene. In this study, using orthotopic metastasis assays and genetically engineered mouse models, we show that one of the enzymatic subunits of the CCR4-NOT complex, Cnot7, is also a metastasis modifying gene. We demonstrate that higher expression of Cnot7 drives tumor cell autonomous metastatic potential, which requires its deadenylase activity. Furthermore, metastasis promotion by CNOT7 is dependent on interaction with CNOT1 and TOB1. CNOT7 ribonucleoprotein-immunoprecipitation (RIP) and integrated transcriptome wide analyses reveal that CNOT7-regulated transcripts are enriched for a tripartite 3'UTR motif bound by RNA-binding proteins known to complex with CNOT7, TOB1, and CNOT1. Collectively, our data support a model of CNOT7, TOB1, CNOT1, and RNA-binding proteins collectively exerting post-transcriptional control on a metastasis suppressive transcriptional program to drive tumor cell metastasis.
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Affiliation(s)
- Farhoud Faraji
- Metastasis Susceptibility Section, Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- School of Medicine, Saint Louis University, Saint Louis, Missouri, United States of America
| | - Ying Hu
- Center for Biomedical Informatics and Information Technology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Howard H. Yang
- Metastasis Susceptibility Section, Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Maxwell P. Lee
- Metastasis Susceptibility Section, Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | | | - Markus Hafner
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kent W. Hunter
- Metastasis Susceptibility Section, Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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26
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The enzyme activities of Caf1 and Ccr4 are both required for deadenylation by the human Ccr4-Not nuclease module. Biochem J 2015; 469:169-76. [PMID: 25944446 PMCID: PMC4613498 DOI: 10.1042/bj20150304] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/06/2015] [Indexed: 01/02/2023]
Abstract
In eukaryotic cells, the shortening and removal of the poly(A) tail (deadenylation) of cytoplasmic mRNA is a key event in regulated mRNA degradation. A major enzyme involved in deadenylation is the Ccr4-Not deadenylase complex, which can be recruited to its target mRNA by RNA-binding proteins or the miRNA repression complex. In addition to six non-catalytic components, the complex contains two enzymatic subunits with ribonuclease activity: Ccr4 and Caf1 (Pop2). In vertebrates, each deadenylase subunit is encoded by two paralogues: Caf1, which can interact with the anti-proliferative protein BTG2, is encoded by CNOT7 and CNOT8, whereas Ccr4 is encoded by the highly similar genes CNOT6 and CNOT6L. Currently, it is unclear whether the catalytic subunits work co-operatively or whether the nuclease components have unique roles in deadenylation. We therefore developed a method to express and purify a minimal human BTG2-Caf1-Ccr4 nuclease sub-complex from bacterial cells. By using chemical inhibition and well-characterized inactivating amino acid substitutions, we demonstrate that the enzyme activities of Caf1 and Ccr4 are both required for deadenylation in vitro. These results indicate that Caf1 and Ccr4 cooperate in mRNA deadenylation and suggest that the enzyme activities of Caf1 and Ccr4 are regulated via allosteric interactions within the nuclease module.
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27
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Yamagishi R, Hosoda N, Hoshino SI. Arsenite inhibits mRNA deadenylation through proteolytic degradation of Tob and Pan3. Biochem Biophys Res Commun 2014; 455:323-31. [PMID: 25446091 DOI: 10.1016/j.bbrc.2014.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 11/07/2014] [Indexed: 01/24/2023]
Abstract
The poly(A) tail of mRNAs plays pivotal roles in the posttranscriptional control of gene expression at both translation and mRNA stability. Recent findings demonstrate that the poly(A) tail is globally stabilized by some stresses. However, the mechanism underlying this phenomenon has not been elucidated. Here, we show that arsenite-induced oxidative stress inhibits deadenylation of mRNA primarily through downregulation of Tob and Pan3, both of which mediate the recruitment of deadenylases to mRNA. Arsenite selectively induces the proteolytic degradation of Tob and Pan3, and siRNA-mediated knockdown of Tob and Pan3 recapitulates stabilization of the mRNA poly(A) tail observed during arsenite stress. Although arsenite also inhibits translation by activating the eIF2α kinase HRI, arsenite-induced mRNA stabilization can be observed under HRI-depleted conditions. These results highlight the essential role of Tob and Pan3 in the stress-induced global stabilization of mRNA.
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Affiliation(s)
- Ryota Yamagishi
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Nao Hosoda
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Shin-ichi Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
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28
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Chapat C, Corbo L. Novel roles of the CCR4-NOT complex. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:883-901. [PMID: 25044499 DOI: 10.1002/wrna.1254] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 06/02/2014] [Accepted: 06/04/2014] [Indexed: 12/21/2022]
Abstract
The CCR4-NOT complex is a multi-subunit protein complex evolutionarily conserved across eukaryotes which regulates several aspects of gene expression. A fascinating model is emerging in which this complex acts as a regulation platform, controlling gene products 'from birth to death' through the coordination of different cellular machineries involved in diverse cellular functions. Recently the CCR4-NOT functions have been extended to the control of the innate immune response through the regulation of interferon signaling. Thus, a more comprehensive picture of how CCR4-NOT allows the rapid adaptation of cells to external stress, from transcription to mRNA and protein decay, is presented and discussed here. Overall, CCR4-NOT permits the efficient and rapid adaptation of cellular gene expression in response to changes in environmental conditions and stimuli.
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Affiliation(s)
- Clément Chapat
- Université Lyon 1, Lyon, France; CNRS UMR 5286, Lyon, France; Inserm U1052, Lyon, France; Cancer Research Center of Lyon, Centre Léon Bérard, Lyon, France
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Inada T, Makino S. Novel roles of the multi-functional CCR4-NOT complex in post-transcriptional regulation. Front Genet 2014; 5:135. [PMID: 24904636 PMCID: PMC4033010 DOI: 10.3389/fgene.2014.00135] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/25/2014] [Indexed: 11/30/2022] Open
Abstract
The CCR4-NOT complex is a highly conserved specific gene silencer that also serves more general post-transcriptional functions. Specific regulatory proteins including the miRNA-induced silencing complex and its associated proteins, bind to 3’-UTR elements of mRNA and recruit the CCR4-NOT complex thereby promoting poly(A) shortening and repressing translation and/or mRNA degradation. Recent studies have shown that the CCR4-NOT complex that is tethered to mRNA by such regulator(s) represses translation and facilitates mRNA decay independent of a poly(A) tail and its shortening. In addition to deadenylase activity, the CCR4-NOT complex also has an E3 ubiquitin ligase activity and is involved in a novel protein quality control system, i.e., co-translational proteasomal-degradation of aberrant proteins. In this review, we describe recent progress in elucidation of novel roles of the multi-functional complex CCR4-NOT in post-transcriptional regulation.
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Affiliation(s)
- Toshifumi Inada
- Laboratory of Gene Regulation, Graduate School of Pharmaceutical Sciences, Tohoku University Sendai, Japan
| | - Shiho Makino
- Laboratory of Gene Regulation, Graduate School of Pharmaceutical Sciences, Tohoku University Sendai, Japan
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30
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Yan YB. Deadenylation: enzymes, regulation, and functional implications. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:421-43. [PMID: 24523229 DOI: 10.1002/wrna.1221] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/20/2013] [Accepted: 12/21/2013] [Indexed: 12/27/2022]
Abstract
Lengths of the eukaryotic messenger RNA (mRNA) poly(A) tails are dynamically changed by the opposing effects of poly(A) polymerases and deadenylases. Modulating poly(A) tail length provides a highly regulated means to control almost every stage of mRNA lifecycle including transcription, processing, quality control, transport, translation, silence, and decay. The existence of diverse deadenylases with distinct properties highlights the importance of regulating poly(A) tail length in cellular functions. The deadenylation activity can be modulated by subcellular locations of the deadenylases, cis-acting elements in the target mRNAs, trans-acting RNA-binding proteins, posttranslational modifications of deadenylase and associated factors, as well as transcriptional and posttranscriptional regulation of the deadenylase genes. Among these regulators, the physiological functions of deadenylases are largely dependent on the interactions with the trans-acting RNA-binding proteins, which recruit deadenylases to the target mRNAs. The task of these RNA-binding proteins is to find and mark the target mRNAs based on their sequence features. Regulation of the regulators can switch on or switch off deadenylation and thereby destabilize or stabilize the targeted mRNAs, respectively. The distinct domain compositions and cofactors provide various deadenylases the structural basis for the recruitments by distinct RNA-binding protein subsets to meet dissimilar cellular demands. The diverse deadenylases, the numerous types of regulators, and the reversible posttranslational modifications together make up a complicated network to precisely regulate intracellular mRNA homeostasis. This review will focus on the diverse regulators of various deadenylases and will discuss their functional implications, remaining problems, and future challenges.
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Affiliation(s)
- Yong-Bin Yan
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
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31
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Winkler GS, Balacco DL. Heterogeneity and complexity within the nuclease module of the Ccr4-Not complex. Front Genet 2013; 4:296. [PMID: 24391663 PMCID: PMC3870282 DOI: 10.3389/fgene.2013.00296] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/04/2013] [Indexed: 11/13/2022] Open
Abstract
The shortening of the poly(A) tail of cytoplasmic mRNA (deadenylation) is a pivotal step in the regulation of gene expression in eukaryotic cells. Deadenylation impacts on both regulated mRNA decay as well as the rate of mRNA translation. An important enzyme complex involved in poly(A) shortening is the Ccr4-Not deadenylase. In addition to at least six non-catalytic subunits, it contains two distinct subunits with ribonuclease activity: a Caf1 subunit, characterized by a DEDD (Asp-Glu-Asp-Asp) domain, and a Ccr4 component containing an endonuclease-exonuclease-phosphatase (EEP) domain. In vertebrate cells, the complexity of the complex is further increased by the presence of paralogs of the Caf1 subunit (encoded by either CNOT7 or CNOT8) and the occurrence of two Ccr4 paralogs (encoded by CNOT6 or CNOT6L). In plants, there are also multiple Caf1 and Ccr4 paralogs. Thus, the composition of the Ccr4-Not complex is heterogeneous. The potential differences in the intrinsic enzymatic activities of the paralogs will be discussed. In addition, the potential redundancy, cooperation, and/or the extent of unique roles for the deadenylase subunits of the Ccr4-Not complex will be reviewed. Finally, novel approaches to study the catalytic roles of the Caf1 and Ccr4 subunits will be discussed.
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Affiliation(s)
- G Sebastiaan Winkler
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, University Park Nottingham, UK
| | - Dario L Balacco
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, University Park Nottingham, UK
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Biochemical and biophysical characterization of the deadenylase CrCaf1 from Chlamydomonas reinhardtii. PLoS One 2013; 8:e69582. [PMID: 23936053 PMCID: PMC3720613 DOI: 10.1371/journal.pone.0069582] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/14/2013] [Indexed: 01/02/2023] Open
Abstract
The modulation of mRNA turnover has been increasingly recognized as a hotpoint for gene expression regulation at the post-transcriptional level. In eukaryotic cells, most mRNAs are degraded via the deadenylation-dependent pathway, in which the removal of the poly(A) tail is the initial and rate-limiting step. Caf1, a deadenylase specifically degrades poly(A) from the 3′-end, is highly conserved from yeast to mammalians. Caf1s in higher plants have been shown to be involved in plant development and stress response. However, little is known about the biochemical and biophysical properties of Caf1s in plants. In this research, we cloned the crcaf1 gene from Chlamydomonas reinhardtii and studied the properties of the recombinant proteins. The results showed that CrCaf1 was a deadenylase with conserved sequence motifs, structural features, and catalytic properties of the Caf1 family. CrCaf1 degraded poly(A) in a distributive mode with the optimal reacting conditions at pH 7 and 35°C. CrCaf1 had similar activity when coordinated with Mg2+ and Mn2+, while the enzyme bound to Ca2+ or Zn2+ was almost inactivated. Zn2+ could induce CrCaf1 aggregation with the disruption of the native structure, while Mg2+, Mn2+ and Ca2+ could stabilize CrCaf1 against thermal denaturation by reducing protein aggregation. Among the various metal ions, Mn2+ showed the strongest protective effect on CrCaf1 stability, implying that Mn2+ might play a role in regulating CrCaf1 stability in the C. reinhardtii cells under some stressed conditions. These findings provide a starting point for further investigation of the physiological functions of CrCaf1 in C. reinhardtii.
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Zhang C, Lee DJ, Chiang YC, Richardson R, Park S, Wang X, Laue TM, Denis CL. The RRM1 domain of the poly(A)-binding protein from Saccharomyces cerevisiae is critical to control of mRNA deadenylation. Mol Genet Genomics 2013; 288:401-12. [PMID: 23793387 DOI: 10.1007/s00438-013-0759-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 06/07/2013] [Indexed: 10/26/2022]
Abstract
The poly(A)-binding protein PAB1 from the yeast Saccharomyces cerevisiae plays an important role in controlling mRNA deadenylation rates. Deletion of either its RRM1 or proline-rich domain (P domain) severely restricts deadenylation and slows mRNA degradation. Because these large deletions could be having unknown effects on the structure of PAB1, different strategies were used to determine the importance of the RRM1 and P domains to deadenylation. Since the P domain is quite variable in size and sequence among eukaryotes, P domains from two human PABPCs and from Xenopus were substituted for that of PAB1. The resultant PAB1 hybrid proteins, however, displayed limited or no difference in mRNA deadenylation as compared with PAB1. In contrast to the P domain, the RRM1 domain is highly conserved across species, and a systematic mutagenesis of the RRM1 domain was undertaken to identify its functional regions. Several mutations along the RNA-binding surface of RRM1 inhibited deadenylation, whereas one set of mutations on its exterior non-RNA binding surface shifted deadenylation from a slow distributive process to a rapid processive deadenylation. These results suggest that the RRM1 domain is the more critical region of PAB1 for controlling deadenylation and consists of at least two distinguishable functional regions.
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Affiliation(s)
- Chongxu Zhang
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, USA
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Wahle E, Winkler GS. RNA decay machines: deadenylation by the Ccr4-not and Pan2-Pan3 complexes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:561-70. [PMID: 23337855 DOI: 10.1016/j.bbagrm.2013.01.003] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/14/2012] [Accepted: 01/09/2013] [Indexed: 12/20/2022]
Abstract
Shortening and removal of the 3' poly(A) tail of mature mRNA by poly(A)-specific 3' exonucleases (deadenylases) is the initial and often rate-limiting step in mRNA degradation. The majority of cytoplasmic deadenylase activity is associated with the Ccr4-Not and Pan2-Pan3 complexes. Two distinct catalytic subunits, Caf1/Pop2 and Ccr4, are associated with the Ccr4-Not complex, whereas the Pan2 enzymatic subunit forms a stable complex with Pan3. In this review, we discuss the composition and activity of these two deadenylases. In addition, we comment on generic and specific mechanisms of recruitment of Ccr4-Not and Pan2-Pan3 to mRNAs. Finally, we discuss specialised and redundant functions of the deadenylases and review the importance of Ccr4-Not subunits in the regulation of physiological processes. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Affiliation(s)
- Elmar Wahle
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany.
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35
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Ogami K, Hosoda N, Funakoshi Y, Hoshino S. Antiproliferative protein Tob directly regulates c-myc proto-oncogene expression through cytoplasmic polyadenylation element-binding protein CPEB. Oncogene 2012. [PMID: 23178487 DOI: 10.1038/onc.2012.548] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The regulation of mRNA deadenylation constitutes a pivotal mechanism of the post-transcriptional control of gene expression. Here we show that the antiproliferative protein Tob, a component of the Caf1-Ccr4 deadenylase complex, is involved in regulating the expression of the proto-oncogene c-myc. The c-myc mRNA contains cis elements (CPEs) in its 3'-untranslated region (3'-UTR), which are recognized by the cytoplasmic polyadenylation element-binding protein (CPEB). CPEB recruits Caf1 deadenylase through interaction with Tob to form a ternary complex, CPEB-Tob-Caf1, and negatively regulates the expression of c-myc by accelerating the deadenylation and decay of its mRNA. In quiescent cells, c-myc mRNA is destabilized by the trans-acting complex (CPEB-Tob-Caf1), while in cells stimulated by the serum, both Tob and Caf1 are released from CPEB, and c-Myc expression is induced early after stimulation by the stabilization of its mRNA as an 'immediate-early gene'. Collectively, these results indicate that Tob is a key factor in the regulation of c-myc gene expression, which is essential for cell growth. Thus, Tob appears to function in the control of cell growth at least, in part, by regulating the expression of c-myc.
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Affiliation(s)
- K Ogami
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - N Hosoda
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Y Funakoshi
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - S Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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36
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Van Etten J, Schagat TL, Hrit J, Weidmann CA, Brumbaugh J, Coon JJ, Goldstrohm AC. Human Pumilio proteins recruit multiple deadenylases to efficiently repress messenger RNAs. J Biol Chem 2012; 287:36370-83. [PMID: 22955276 PMCID: PMC3476303 DOI: 10.1074/jbc.m112.373522] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 09/05/2012] [Indexed: 11/06/2022] Open
Abstract
PUF proteins are a conserved family of eukaryotic RNA-binding proteins that regulate specific mRNAs: they control many processes including stem cell proliferation, fertility, and memory formation. PUFs repress protein expression from their target mRNAs but the mechanism by which they do so remains unclear, especially for humans. Humans possess two PUF proteins, PUM1 and PUM2, which exhibit similar RNA binding specificities. Here we report new insights into their regulatory activities and mechanisms of action. We developed functional assays to measure sequence-specific repression by PUM1 and PUM2. Both robustly inhibit translation and promote mRNA degradation. Purified PUM complexes were found to contain subunits of the CCR4-NOT (CNOT) complex, which contains multiple enzymes that catalyze mRNA deadenylation. PUMs interact with the CNOT deadenylase subunits in vitro. We used three approaches to determine the importance of deadenylases for PUM repression. First, dominant-negative mutants of CNOT7 and CNOT8 reduced PUM repression. Second, RNA interference depletion of the deadenylases alleviated PUM repression. Third, the poly(A) tail was necessary for maximal PUM repression. These findings demonstrate a conserved mechanism of PUF-mediated repression via direct recruitment of the CCR4-POP2-NOT deadenylase leading to translational inhibition and mRNA degradation. A second, deadenylation independent mechanism was revealed by the finding that PUMs repress an mRNA that lacks a poly(A) tail. Thus, human PUMs are repressors capable of deadenylation-dependent and -independent modes of repression.
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Affiliation(s)
- Jamie Van Etten
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
| | - Trista L. Schagat
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
- the Promega Corporation, Madison, Wisconsin 53711, and
| | - Joel Hrit
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
| | - Chase A. Weidmann
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
| | - Justin Brumbaugh
- the Departments of Chemistry and Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Joshua J. Coon
- the Departments of Chemistry and Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Aaron C. Goldstrohm
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
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37
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Abstract
Shortening of the poly(A) tail is the first and often rate-limiting step in mRNA degradation. Three poly(A)-specific 3' exonucleases have been described that can carry out this reaction: PAN, composed of two subunits; PARN, a homodimer; and the CCR4-NOT complex, a heterooligomer that contains two catalytic subunits and may have additional functions in the cell. Current evidence indicates that all three enzymes use a two-metal ion mechanism to release nucleoside monophosphates in a hydrolytic reaction. The CCR4-NOT is the main deadenylase in all organisms examined, and mutations affecting the complex can be lethal. The contribution of PAN, apparently an initial deadenylation preceding the activity of CCR4-NOT, is less important, whereas the activity of PARN seems to be restricted to specific substrates or circumstances, for example, stress conditions. Rapid deadenylation and decay of specific mRNAs can be caused by recruitment of both PAN and the CCR4-NOT complex. This function can be carried out by RNA-binding proteins, for example, members of the PUF family. Alternatively, miRNAs can recruit the deadenylase complexes with the help of their associated GW182 proteins.
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Affiliation(s)
- Christiane Harnisch
- Martin-Luther-University of Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, Halle, Germany
| | - Bodo Moritz
- Martin-Luther-University of Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, Halle, Germany
| | - Christiane Rammelt
- Martin-Luther-University of Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, Halle, Germany
| | - Claudia Temme
- Martin-Luther-University of Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, Halle, Germany
| | - Elmar Wahle
- Martin-Luther-University of Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, Halle, Germany.
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38
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Abstract
The purpose of this review is to provide an analysis of the latest developments on the functions of the carbon catabolite-repression 4-Not (Ccr4-Not) complex in regulating eukaryotic gene expression. Ccr4-Not is a nine-subunit protein complex that is conserved in sequence and function throughout the eukaryotic kingdom. Although Ccr4-Not has been studied since the 1980s, our understanding of what it does is constantly evolving. Once thought to solely regulate transcription, it is now clear that it has much broader roles in gene regulation, such as in mRNA decay and quality control, RNA export, translational repression and protein ubiquitylation. The mechanism of actions for each of its functions is still being debated. Some of the difficulty in drawing a clear picture is that it has been implicated in so many processes that regulate mRNAs and proteins in both the cytoplasm and the nucleus. We will describe what is known about the Ccr4-Not complex in yeast and other eukaryotes in an effort to synthesize a unified model for how this complex coordinates multiple steps in gene regulation and provide insights into what questions will be most exciting to answer in the future.
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Affiliation(s)
- Jason E. Miller
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Center for RNA Molecular Biology, Penn State University, University Park, PA 16802
| | - Joseph C. Reese
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Center for RNA Molecular Biology, Penn State University, University Park, PA 16802
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39
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Abstract
All RNA species in yeast cells are subject to turnover. Work over the past 20 years has defined degradation mechanisms for messenger RNAs, transfer RNAs, ribosomal RNAs, and noncoding RNAs. In addition, numerous quality control mechanisms that target aberrant RNAs have been identified. Generally, each decay mechanism contains factors that funnel RNA substrates to abundant exo- and/or endonucleases. Key issues for future work include determining the mechanisms that control the specificity of RNA degradation and how RNA degradation processes interact with translation, RNA transport, and other cellular processes.
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Affiliation(s)
- Roy Parker
- Department of Molecular and Cellular Biology, University of Arizona and Howard Hughes Medical Institute, Tucson, AZ 85721, USA.
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40
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Feng LK, Yan YB. The N-terminus modulates human Caf1 activity, structural stability and aggregation. Int J Biol Macromol 2012; 51:497-503. [PMID: 22683897 DOI: 10.1016/j.ijbiomac.2012.05.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 05/24/2012] [Accepted: 05/29/2012] [Indexed: 12/22/2022]
Abstract
Caf1 is a deadenylase component of the CCR4-Not complex. Here we found that the removal of the N-terminus resulted in a 30% decrease in human Caf1 (hCaf1) activity, but had no significant influence on main domain structure. The removal of the N-terminus led to a decrease in the thermal stability, while the existence of the N-terminus promoted hCaf1 thermal aggregation. Homology modeling indicated that the N-terminus had a potency to form a short α-helix interacted with the main domain. Thus the N-terminus played a role in modulating hCaf1 activity, stability and aggregation.
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Affiliation(s)
- Li-Kui Feng
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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41
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Evidence providing new insights into TOB-promoted deadenylation and supporting a link between TOB's deadenylation-enhancing and antiproliferative activities. Mol Cell Biol 2012; 32:1089-98. [PMID: 22252318 DOI: 10.1128/mcb.06370-11] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The mammalian TOB1 and TOB2 proteins have emerged as key players in repressing cell proliferation. Accumulating evidence indicates that TOBs regulate mRNA deadenylation. A recruitment model was proposed in which TOBs promote deadenylation by recruiting CAF1-CCR4 deadenylase complex to the 3' end of mRNAs by simultaneously binding CAF1 and PABP. However, the exact molecular mechanism underlying TOB-promoted deadenylation remains unclear. It is also unclear whether TOBs' antiproliferative and deadenylation-promoting activities are connected. Here, we combine biochemical analyses with a functional assay directly monitoring deadenylation and mRNA decay to characterize the effects of tethering TOBs or their mutant derivatives to mRNAs. The results provide direct evidence supporting the recruitment model and reveal a link between TOBs' antiproliferative and deadenylation-promoting activities. We also find that TOBs' actions in deadenylation are independent of the phosphorylation state of three serines known to regulate antiproliferative actions, suggesting that TOBs arrest cell growth through at least two different mechanisms. TOB1 and TOB2 were interchangeable in the properties tested here, indicating considerable functional redundancy between the two proteins. We propose that their multiple modes of modulating mRNA turnover and arresting cell growth permit the TOB proteins to coordinate their diverse roles in controlling cell growth and differentiation.
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42
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Collart MA, Panasenko OO. The Ccr4--not complex. Gene 2011; 492:42-53. [PMID: 22027279 DOI: 10.1016/j.gene.2011.09.033] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/06/2011] [Accepted: 09/29/2011] [Indexed: 12/11/2022]
Abstract
The Ccr4-Not complex is a unique, essential and conserved multi-subunit complex that acts at the level of many different cellular functions to regulate gene expression. Two enzymatic activities, namely ubiquitination and deadenylation, are provided by different subunits of the complex. However, studies over the last decade have demonstrated a tantalizing multi-functionality of this complex that extends well beyond its identified enzymatic activities. Most of our initial knowledge about the Ccr4-Not complex stemmed from studies in yeast, but an increasing number of reports on this complex in other species are emerging. In this review we will discuss the structure and composition of the complex, and describe the different cellular functions with which the Ccr4-Not complex has been connected in different organisms. Finally, based upon our current state of knowledge, we will propose a model to explain how one complex can provide such multi-functionality. This model suggests that the Ccr4-Not complex might function as a "chaperone platform".
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Affiliation(s)
- Martine A Collart
- Dpt Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, 1211 Geneva 4, Switzerland.
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43
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Idler RK, Yan W. Control of messenger RNA fate by RNA-binding proteins: an emphasis on mammalian spermatogenesis. ACTA ACUST UNITED AC 2011; 33:309-37. [PMID: 21757510 DOI: 10.2164/jandrol.111.014167] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Posttranscriptional status of messenger RNAs (mRNA) can be affected by many factors, most of which are RNA-binding proteins (RBP) that either bind mRNA in a nonspecific manner or through specific motifs, usually located in the 3' untranslated regions. RBPs can also be recruited by small noncoding RNAs (sncRNA), which have been shown to be involved in posttranscriptional regulations and transposon repression (eg, microRNAs or P-element-induced wimpy testis-interacting RNA) as components of the sncRNA effector complex. Non-sncRNA-binding RBPs have much more diverse effects on their target mRNAs. Some can cause degradation of their target transcripts and/or repression of translation, whereas others can stabilize and/or activate translation. The splicing and exportation of transcripts from the nucleus to the cytoplasm are often mediated by sequence-specific RBPs. The mechanisms by which RBPs regulate mRNA transcripts involve manipulating the 3' poly(A) tail, targeting the transcript to polysomes or to other ribonuclear protein particles, recruiting regulatory proteins, or competing with other RBPs. Here, we briefly review the known mechanisms of posttranscriptional regulation mediated by RBPs, with an emphasis on how these mechanisms might control spermatogenesis in general.
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Affiliation(s)
- R Keegan Idler
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Kerr SC, Azzouz N, Fuchs SM, Collart MA, Strahl BD, Corbett AH, Laribee RN. The Ccr4-Not complex interacts with the mRNA export machinery. PLoS One 2011; 6:e18302. [PMID: 21464899 PMCID: PMC3065485 DOI: 10.1371/journal.pone.0018302] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 03/02/2011] [Indexed: 11/19/2022] Open
Abstract
Background The Ccr4-Not complex is a key eukaryotic regulator of gene transcription and cytoplasmic mRNA degradation. Whether this complex also affects aspects of post-transcriptional gene regulation, such as mRNA export, remains largely unexplored. Human Caf1 (hCaf1), a Ccr4-Not complex member, interacts with and regulates the arginine methyltransferase PRMT1, whose targets include RNA binding proteins involved in mRNA export. However, the functional significance of this regulation is poorly understood. Methodology/Principal Findings Here we demonstrate using co-immunoprecipitation approaches that Ccr4-Not subunits interact with Hmt1, the budding yeast ortholog of PRMT1. Furthermore, using genetic and biochemical approaches, we demonstrate that Ccr4-Not physically and functionally interacts with the heterogenous nuclear ribonucleoproteins (hnRNPs) Nab2 and Hrp1, and that the physical association depends on Hmt1 methyltransferase activity. Using mass spectrometry, co-immunoprecipitation and genetic approaches, we also uncover physical and functional interactions between Ccr4-Not subunits and components of the nuclear pore complex (NPC) and we provide evidence that these interactions impact mRNA export. Conclusions/Significance Taken together, our findings suggest that Ccr4-Not has previously unrealized functional connections to the mRNA processing/export pathway that are likely important for its role in gene expression. These results shed further insight into the biological functions of Ccr4-Not and suggest that this complex is involved in all aspects of mRNA biogenesis, from the regulation of transcription to mRNA export and turnover.
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Affiliation(s)
- Shana C. Kerr
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Department of Biochemistry, Cell, and Developmental Biology Graduate Program, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Nowel Azzouz
- Department of Microbiology and Molecular Medicine, University of Geneva Medical School, Geneva, Switzerland
| | - Stephen M. Fuchs
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Martine A. Collart
- Department of Microbiology and Molecular Medicine, University of Geneva Medical School, Geneva, Switzerland
| | - Brian D. Strahl
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Anita H. Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine and Center for Cancer Research, University of Tennessee Health Sciences Center, Memphis, Tennessee, United States of America
- * E-mail:
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Abstract
The poly(A) tail of mRNA has an important influence on the dynamics of gene expression. On one hand, it promotes enhanced mRNA stability to allow production of the protein, even after inactivation of transcription. On the other hand, shortening of the poly(A) tail (deadenylation) slows down translation of the mRNA, or prevents it entirely, by inducing mRNA decay. Thus deadenylation plays a crucial role in the post-transcriptional regulation of gene expression, deciding the fate of individual mRNAs. It acts both in basal mRNA turnover, as well as in temporally and spatially regulated translation and decay of specific mRNAs. In the present paper, we discuss mRNA deadenylation in eukaryotes, focusing on the main deadenylase, the Ccr4-Not complex, including its composition, regulation and functional roles.
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Anti-proliferative protein Tob negatively regulates CPEB3 target by recruiting Caf1 deadenylase. EMBO J 2011; 30:1311-23. [PMID: 21336257 DOI: 10.1038/emboj.2011.37] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 01/24/2011] [Indexed: 01/17/2023] Open
Abstract
Tob is a member of the anti-proliferative protein family, which functions in transcription and mRNA decay. We have previously demonstrated that Tob is involved in the general mechanism of mRNA decay by mediating mRNA deadenylation through interaction with Caf1 and a general RNA-binding protein, PABPC1. Here, we focus on the role of Tob in the regulation of specific mRNA. We show that Tob binds directly to a sequence-specific RNA-binding protein, cytoplasmic polyadenylation element-binding protein 3 (CPEB3). CPEB3 negatively regulates the expression of a target by accelerating deadenylation and decay of its mRNA, which it achieves by tethering to the mRNA. The carboxyl-terminal RNA-binding domain of CPEB3 binds to the carboxyl-terminal unstructured region of Tob. Tob then binds Caf1 deadenylase and recruits it to CPEB3 to form a ternary complex. The CPEB3-accelerated deadenylation was abrogated by a dominant-negative mutant of either Caf1 or Tob. Together, these results indicate that Tob mediates the recruitment of Caf1 to the target of CPEB3 and elicits deadenylation and decay of the mRNA. Our results provide an explanation of how Tob regulates specific biological processes.
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Becerra M, Lombardía LJ, Lamas-Maceiras M, Canto E, Rodríguez-Belmonte E, Cerdán ME. Comparative transcriptome analysis of yeast strains carrying slt2, rlm1, and pop2 deletions. Genome 2011; 54:99-109. [DOI: 10.1139/g10-101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The function of the genes SLT2 (encoding the Mpk1 protein), RLM1, and POP2 have previously been related to several stress responses in yeasts. DNA arrays have been used to identify differences among the transcriptomes of a Saccharomyces cerevisiae wild type strain and its derivative Δslt2, Δrlm1, and Δpop2 mutants. Correspondence analyses indicate that the vast majority of genes that show lower expression in Δrlm1 also show lower expression in Δslt2. In contrast, there is little overlap between the results of the transcriptome analyses of the Δpop2 strain and the Δslt2 or Δrlm1 strains. The DNA array data were validated by reverse Northern blotting and chromatin immunoprecipitation (ChIp). ChIp assays demonstrate Rlm1p binding to specific regions of the promoters of two genes that show expression differences between the Δrlm1 mutant and wild type strains. Interestingly, RLM1 deletion decreases the transcription of SLT2, encoding the Mpk1p kinase that phosphorylates Rlm1p, suggesting a feedback control in the signal transduction pathway. Also, deletion of RLM1 causes a decrease in the mRNA level of KDX1, which is paralogous to SLT2. In contrast, deletion of POP2 is accompanied by an increase of both SLT2 and KDX1 levels. We show that SLT2 mRNA increase in the Δpop2 strain is due to a decrease in RNA turnover, consistent with the expected loss of RNA-deadenylase activity in this strain.
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Affiliation(s)
- M. Becerra
- Dpto. Bioloxía Celular e Molecular, Universidade da Coruña, F Ciencias, Campus da Zapateira s/n 15071, A Coruña, Spain
- Molecular Diagnostics Unit - Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas (Spanish National Cancer Research Centre)
| | - L. J. Lombardía
- Dpto. Bioloxía Celular e Molecular, Universidade da Coruña, F Ciencias, Campus da Zapateira s/n 15071, A Coruña, Spain
- Molecular Diagnostics Unit - Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas (Spanish National Cancer Research Centre)
| | - M. Lamas-Maceiras
- Dpto. Bioloxía Celular e Molecular, Universidade da Coruña, F Ciencias, Campus da Zapateira s/n 15071, A Coruña, Spain
- Molecular Diagnostics Unit - Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas (Spanish National Cancer Research Centre)
| | - E. Canto
- Dpto. Bioloxía Celular e Molecular, Universidade da Coruña, F Ciencias, Campus da Zapateira s/n 15071, A Coruña, Spain
- Molecular Diagnostics Unit - Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas (Spanish National Cancer Research Centre)
| | - E. Rodríguez-Belmonte
- Dpto. Bioloxía Celular e Molecular, Universidade da Coruña, F Ciencias, Campus da Zapateira s/n 15071, A Coruña, Spain
- Molecular Diagnostics Unit - Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas (Spanish National Cancer Research Centre)
| | - M. E. Cerdán
- Dpto. Bioloxía Celular e Molecular, Universidade da Coruña, F Ciencias, Campus da Zapateira s/n 15071, A Coruña, Spain
- Molecular Diagnostics Unit - Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas (Spanish National Cancer Research Centre)
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Mittal S, Aslam A, Doidge R, Medica R, Winkler GS. The Ccr4a (CNOT6) and Ccr4b (CNOT6L) deadenylase subunits of the human Ccr4-Not complex contribute to the prevention of cell death and senescence. Mol Biol Cell 2011; 22:748-58. [PMID: 21233283 PMCID: PMC3057700 DOI: 10.1091/mbc.e10-11-0898] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The human Ccr4-Not complex has two types of deadenylase subunits that shorten the polyadenylate tail of cytoplasmic mRNA. The authors present evidence for novel roles of the highly related Ccr4a/Ccr4b deadenylases in preventing cell death and senescence and show that they have distinct roles as compared with the Caf1a/Caf1b deadenylases. A key step in cytoplasmic mRNA degradation is the shortening of the poly(A) tail, which involves several deadenylase enzymes. Relatively little is known about the importance of these enzymes for the cellular physiology. Here we focused on the role of the highly similar Ccr4a (CNOT6) and Ccr4b (CNOT6L) deadenylase subunits of the Ccr4–Not complex. In addition to a role in cell proliferation, Ccr4a and Ccr4b play a role in cell survival, in contrast to the Caf1a (CNOT7) and Caf1b (CNOT8) deadenylase subunits or the CNOT1 and CNOT3 noncatalytic subunits of the Ccr4–Not complex. Underscoring the differential contributions of the deadenylase subunits, we found that knockdown of Caf1a/Caf1b or Ccr4a/Ccr4b differentially affects the formation of cytoplasmic foci by processing-body components. Furthermore, we demonstrated that the amino-terminal leucine-rich repeat (LRR) domain of Ccr4b influenced its subcellular localization but was not required for the deadenylase activity of Ccr4b. Moreover, overexpression of Ccr4b lacking the LRR domain interfered with cell cycle progression but not with cell viability. Finally, gene expression profiling indicated that distinct gene sets are regulated by Caf1a/Caf1b and Ccr4a/Ccr4b and identified Ccr4a/Ccr4b as a key regulator of insulin-like growth factor–binding protein 5, which mediates cell cycle arrest and senescence via a p53-dependent pathway.
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Affiliation(s)
- Saloni Mittal
- School of Pharmacy and Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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Abstract
The CCR4-CAF1-NOT complex is a major cytoplasmic deadenylation complex in yeast and mammals. This complex associates with RNA-binding proteins and microRNAs to repress translation of target mRNAs. We sought to determine how CCR4 and CAF1 participate in repression and control of maternal mRNAs using Xenopus laevis oocytes. We show that Xenopus CCR4 and CAF1 enzymes are active deadenylases and repress translation of an adenylated mRNA. CAF1 also represses translation independent of deadenylation. The deadenylation-independent repression requires a 5' cap structure on the mRNA; however, deadenylation does not. We suggest that mere recruitment of CAF1 is sufficient for repression, independent of deadenylation.
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Affiliation(s)
- Amy Cooke
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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Temme C, Zhang L, Kremmer E, Ihling C, Chartier A, Sinz A, Simonelig M, Wahle E. Subunits of the Drosophila CCR4-NOT complex and their roles in mRNA deadenylation. RNA (NEW YORK, N.Y.) 2010; 16:1356-1370. [PMID: 20504953 PMCID: PMC2885685 DOI: 10.1261/rna.2145110] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 04/16/2010] [Indexed: 05/27/2023]
Abstract
The CCR4-NOT complex is the main enzyme catalyzing the deadenylation of mRNA. We have investigated the composition of this complex in Drosophila melanogaster by immunoprecipitation with a monoclonal antibody directed against NOT1. The CCR4, CAF1 (=POP2), NOT1, NOT2, NOT3, and CAF40 subunits were associated in a stable complex, but NOT4 was not. Factors known to be involved in mRNA regulation were prominent among the other proteins coprecipitated with the CCR4-NOT complex, as analyzed by mass spectrometry. The complex was localized mostly in the cytoplasm but did not appear to be a major component of P bodies. Of the known CCR4 paralogs, Nocturnin was found associated with the subunits of the CCR4-NOT complex, whereas Angel and 3635 were not. RNAi experiments in Schneider cells showed that CAF1, NOT1, NOT2, and NOT3 are required for bulk poly(A) shortening and hsp70 mRNA deadenylation, but knock-down of CCR4, CAF40, and NOT4 did not affect these processes. Overexpression of catalytically dead CAF1 had a dominant-negative effect on mRNA decay. In contrast, overexpression of inactive CCR4 had no effect. We conclude that CAF1 is the major catalytically important subunit of the CCR4-NOT complex in Drosophila Schneider cells. Nocturnin may also be involved in mRNA deadenylation, whereas there is no evidence for a similar role of Angel and 3635.
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Affiliation(s)
- Claudia Temme
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
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